The pair exchanged 389 calls and texts between 2009 and 2011, many of which were subsequently deleted, including one that the NSW Police Force argued was proof that he met Mr Ghassibe at the back of the towing company's workshop one day to collect $1000.

"The workers are nearly gone so text me when you are here," Ghassibe wrote.

"I'm around the corner," Cottrell replied.

In a 5½ year legal battle, including almost three years in which Mr Cottrell was suspended on full pay, the Industrial Relations Commission finally handed down a ruling this month and upheld the force's decision to sack him.

Fifteen months after a three-day hearing at the IRC, Mr Cotterell's case that it was a "harsh, unreasonable or unjust removal" was dismissed.

Police stations in NSW use a rostered system of two truck companies to call out to crashes to avoid favouritism. Photo: Michele Mossop

In late 2011, friction between tow truck companies in the St George area over who controlled various patches became increasingly heated.

It led one operator to tell the police that his rival, Mr Ghassibe, was receiving tip-offs from two officers.

Mr Cotterell told the IRC that he used Mr Ghassibe, who no longer works for St George Towing, as a "work tool" and texted him the addresses of crashes.

He said he was reprimanded once for waiting four hours at a crash site for a tow truck to arrive, thereby missing a robbery call, so he started texting the only company he knew in the area in order to prevent delays.

Even if Mr Cottrell wasn't attending the crash, he would text Mr Ghassibe, because he provided "excellent service".

David Cottrell. Photo: Supplied

He maintained it was a purely professional relationship and there was no obvious benefit to Mr Ghassibe as car owners weren't obliged to use him.

"I never told anyone they had to use him," he said. "My concern was clearing the road."

He strongly denied he received a $1000 "spotter's fee" and accused a colleague, Constable Andrew Vrahas, of making up the claim to deflect attention as he was also close with Mr Ghassibe.

Following several internal investigations and a criminal prosecution for bribery that fell over due to lack of evidence, the NSW Police Commissioner dismissed him in 2015 for passing on confidential information, not declaring a conflict of interest and receiving a bribe.

In the IRC, the police said his lack of insight into the seriousness was concerning.

They said his explanation that he texted Mr Ghassibe out of "diligence and efficiency" was belied by the fact he had been previously reprimanded for laziness, sleeping on the job, passing work off to junior staff, failing to attend court and not recording the details of offences properly.

IRC Commissioner Inaam Tabbaa found that Mr Cotterell took the bribe.

"Considered in light of his emphatic denials and the finding that he received a benefit for the tip-offs, I do not find that the termination was unjust," he said.

The NSW Police Force's standard operating procedures say that police stations should have a rostered system of two truck companies to call out to crashes to avoid favouritism.